Shower base



FIG. 1 is a front perspective view showing the design;

FIG. 2 is a rear perspective view thereof;

FIG. 3 is a top view thereof;

FIG. 4 is a side view thereof;

FIG. 5 is a rear view thereof; and,

FIG. 6 is a front view thereof.

CLAIM The ornamental design of a shower base, as shown and described.